This patent application claims priority to German Patent Application No. 100 60 219.3-51 filed Dec. 4, 2000.
The invention relates to a hard-rolling machine for crankshafts according to the preamble of the main claim.
During hard rolling of recesses or radii on crankshafts there is a possibility that the crankshaft may buckle. Because of this purpose the crankshaft is measured after the hard-rolling operation to determine whether it exhibits any eccentricity. This measurement is generally made using measuring probes which are lowered onto one or several of the main bearings of the crankshaft after the hard-rolling operation and are connected electrically to an evaluation device. During the measurement the crankshaft makes one revolution about its longitudinal axis. The quality of the hard-rolled crankshaft is determined by allocating one measuring probe respectively to each of the crankshaft main bearings. According to the measurement result a further hard-rolling operation can then follow in which the radii or recesses of individual bearing sites are specifically re-rolled. This re-rolling can extend over the entire circumference of the relevant bearing site or it can however merely involve part of the circumference. This re-rolling can embrace the radii or recesses at individual main bearings or at crankpin bearings of the crankshaft.
High requirements are imposed on the measurement accuracy of the eccentricity measurement. For example, for a crankshaft having an overall length of approximately 400 mm it is still necessary to measure an eccentricity at the central main bearing which is of the order of magnitude of 10xe2x88x922 mm.
On the basis of the particular measurement result the hard-rolling operation is regulated at the hard-rolling machine via the evaluation device. Usually a plurality of measuring probes corresponding to each main bearing is arranged along the crankshaft. As a result of the mutual spacings separating the measuring probes one from the other, the configuration is in each case only suitable for a specific type of crankshaft. However, modern hard-rolling machines for crankshafts are designed so that several types of crankshaft can be machined one after the other. This means however that the setting of the measuring probes must be adjusted from one type of crankshaft to another. For example, the hard rolling of a crankshaft for a three-cylinder engine requires a smaller number of measuring probes than the hard-rolling of crankshafts for engines having a larger number of cylinders. Thus, the hard-rolling machine for the crankshafts must be retooled each time when different types of crankshaft are to be machined on it. Regardless of the changing of the hard-rolling tools thus involved, the measuring probes must be re-aligned each time with the required accuracy so that the hard-rolling operation is successful.
Thus the object for the present invention is to attach measuring probes exchangeably to the hard-rolling machine in the required number and in a pre-prepared configuration according to the particular type of crankshaft to be hard-rolled. In addition to the required measurement accuracy, it must also be ensured that the multiple connection of the measuring probes with the evaluation device can be made extremely carefully and reliably and in the shortest time. Finally the time taken to retool from one group of measuring probes to another should be as short as possible and the attachment of the measuring probes should be as easy as possible.
The object is achieved by the characterising features of the main claim. There is provided a measuring-probe bridge on which is provided a plurality of measuring probes corresponding to the number of main bearings to be measured, which are arranged with a mutual spacing one from the other. The measuring-probe bridge can be connected via a quick coupling to the free end of the arm which is provided to engage the measuring probes with the crankshaft. The quick coupling is configured so that at the same time it is also possible to make the cable connection via which the individual measuring probes are connected to the evaluation device. In the present case the cable connection is a multi-pole plug which ensures careful and high-precision joining of the individual cables one to the other, which are assigned to each measuring probe. The quick coupling ensures that the measuring probes can be attached to the hard-rolling machine easily and without canting. At the same time the measuring probes are coupled to the evaluation device with the greatest possible care of the plug connection. Each type of crankshaft is allocated its own measuring-probe bridge on which the individual measuring probes are attached according to type. Since the individual measuring-probe bridges can be exchanged quickly, the setting period of the hard-rolling machine is reduced substantially.
Particularly advantageous is the design of the quick coupling as an adjusting sleeve in which a pin can be inserted to secure measuring probes, which for its part is part of the measuring-probe bridge and can be unlocked by axially sliding a connecting bush. Adjusting sleeves of said type are known for example from DIN 55 058. The adjusting sleeves known from the standard are used to connect tools with the spindle heads of machine tools. On the basis of the DIN standard the adjusting sleeves or tool holders were further developed in such a way that they can changed quickly without additional tools and can be locked by pushing into the spindle of the machine tool. Unlocking is achieved by axially sliding a connecting bush. A corresponding system has been reported under the model designation ASBVA in a publication by Otto Bilz Werkzeugfabrik GmbH and Co., 73760 Ostfildern.
Secure coupling and uncoupling of the measuring probes bridge with the hard-rolling machine is achieved if two arms in the same geometrical configuration are connected secure against rotation to the shaft, these being provided to engage the measuring probes with the crankshaft on the hard-rolling machine. Each of the two arms then also has its own adjusting sleeve. The free ends of the two arms are connected to each other via a plate. The adjusting sleeves for the quick coupling are attached to the plate at the side next to the arms.
In order to ensure that the measuring-probe bridge can be attached to the hard-rolling machine as far as possible without canting and therefore with ease of action, one of the adjusting sleeves is connected via a hinge to the plate which for its part connects the ends of the two arms together. Certain manufacturing tolerances which are unavoidable in the manufacture of a measuring probes bridge can at the same time be taken up by this hinge. By means of this hinge any canting of the measuring-probe bridge as it is attached to the hard-rolling machine is largely excluded whereby the ease of action of the connection and also the measurement accuracy are ensured. In order to protect the electrical contacts parts of the detachable plug connection which lead to the evaluation device are also rigidly connected to the plate.
As is inherently usual, every measuring probe in the position of engagement with the crankshaft is vertical. During hard rolling of the crankshaft the measuring probes are swivelled out of engagement and then assume an approximately horizontal position. In this swung-out position of the measuring probes the hard-rolling tools can hard-roll the radii or necks of the crankshaft unhindered.